System, method, and computer program product for creating a single library image from multiple independent tape libraries

ABSTRACT

In one embodiment, a system includes a library manager for communicating with a plurality of logical libraries having data organized therein and stored on sequential access media therein, wherein the library manager controls movement operations of a plurality of shuttle cars along one or more shuttle pathways, wherein each of the shuttle cars are for transporting a sequential access medium between any of the plurality of logical libraries, wherein each of the logical libraries comprises at least one local station for sending and/or receiving shuttle cars to and/or from the plurality of logical libraries, wherein the one or more shuttle pathways connect the stations in a multi-drop arrangement, wherein each destination station is represented by a unique export-only address, and wherein all source stations are represented by a common import-only address. Other systems, methods, and computer program products are also described according to various embodiments.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to a system for creating a singlelibrary image from multiple independent tape libraries.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers commonly. Data is writtenon the magnetic recording media by moving a magnetic recordingtransducer to a position over the media where the data is to be stored.The magnetic recording transducer then generates a magnetic field, whichencodes the data into the magnetic media. Data is read from the media bysimilarly positioning the magnetic read transducer and then sensing themagnetic field of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

The largest tape archives in the world, if they were to store all thedata that the users demanded, would use more tape cartridges than thereare available, e.g., these systems would exceed the maximum tapecartridge counts of the largest tape libraries offered in the market.However, the storage demands of these archives are met by using multipletape libraries. The most cost-effective way to implement multiple tapelibraries is to physically connect these multiple libraries via a“pass-thru” which is capable of carrying one or more tape cartridgesbetween the libraries to deal with access “hot spots.” An access hotspot is a term which describes a situation where one library experiencesa peak in access demand for the tape cartridges stored therein. In thesesituations, the pass-thru is utilized to offload a portion of theassigned work to tape drives in another, under-utilized and connectedlibrary(ies).

The aggregation of these connected libraries then creates a “singlelibrary image” which can be utilized by higher level applications,rather than relying on a trying to deal with a plurality of libraryimages, numbering N. In the past, the pass-thru technology has beenlimited to point-to-point connection and cartridge movement betweenestablished pairs of libraries. When larger images are being used, ifthe demand increased on both libraries of a pair, to lessen the load, atape cartridge may be moved through one or more intermediary librariesto arrive at an under-utilized library. These may be visualized as thetape equivalent of “connecting flights” that are made from a sourcelibrary, through intermediary library(ies), and finally arriving at thedestination library. Therefore, in order to speed up each transferbetween libraries and also to support a much higher degree ofparallelism in the system, a simple cost-effective method and/or systemcapable of direct access to the plurality of tape libraries would bevery beneficial.

BRIEF SUMMARY

In one embodiment, a system includes a library manager for communicatingwith a plurality of logical libraries having data organized therein andstored on sequential access media therein, wherein the library managercontrols movement operations of a plurality of shuttle cars along one ormore shuttle pathways, wherein each of the shuttle cars are fortransporting a sequential access medium between any of the plurality oflogical libraries, wherein each of the logical libraries comprises atleast one local station for sending and/or receiving shuttle cars toand/or from the plurality of logical libraries, wherein the one or moreshuttle pathways connect the stations in a multi-drop arrangement,wherein each destination station is represented by a unique export-onlyaddress, and wherein all source stations are represented by a commonimport-only address.

In another embodiment, a method includes requesting access to a mediadrive located at a first station for loading a media cartridge therein,wherein the media cartridge is physically located at a second station,and receiving a response indicating a multi-drop unidirectional addressspecified in the response, wherein a shuttle car physically moves themedia cartridge from the second station to the first station.

In another embodiment, a computer program product for managing at leastone logical library includes a computer readable storage medium havingcomputer readable program code embodied therewith, the computer readableprogram code including computer readable program code configured torequest access to a media drive located at a first station for loading amedia cartridge therein, wherein the media cartridge is physicallylocated at a second station, computer readable program code configuredto receive a response indicating a multi-drop unidirectional addressspecified in the response, wherein a shuttle car physically moves themedia cartridge from the second station to the first station.

In another embodiment, a system includes a plurality of logicallibraries, each logical library including at least one sequential accessmedia drive, at least one local station for sending and/or receivingshuttle cars to and/or from the plurality of logical libraries, andsequential access media for storing data therein. The system alsoincludes a library manager for communicating with the plurality oflogical libraries, wherein the library manager controls movementoperations of a plurality of shuttle cars along one or more shuttlepathways, wherein each of the shuttle cars are for transporting asequential access medium between any of the plurality of logicallibraries, wherein the one or more shuttle pathways connect the stationsin a multi-drop arrangement, wherein each destination station isrepresented by a unique export-only address, wherein all source stationsare represented by a common import-only address, and wherein an importelement address for a sequential access medium transferred from a firststation is different than an export element address for the sequentialaccess medium transferred to the first station.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a network architecture, in accordance with oneembodiment.

FIG. 2 shows a representative hardware environment that may beassociated with the servers and/or clients of FIG. 1, in accordance withone embodiment.

FIG. 3 shows an illustrative system, according to one embodiment.

FIG. 4 shows a method for combining components of a plurality of logicallibraries into a single image library, according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofstorage systems, as well as operation and/or component parts thereof.

In one general embodiment, a system includes a library manager forcommunicating with a plurality of logical libraries having dataorganized therein and stored on sequential access media therein, whereinthe library manager controls movement operations of a plurality ofshuttle cars along one or more shuttle pathways, wherein each of theshuttle cars are for transporting a sequential access medium between anyof the plurality of logical libraries, wherein each of the logicallibraries comprises at least one local station for sending and/orreceiving shuttle cars to and/or from the plurality of logicallibraries, wherein the one or more shuttle pathways connect the stationsin a multi-drop arrangement, wherein each destination station isrepresented by a unique export-only address, and wherein all sourcestations are represented by a common import-only address.

In another general embodiment, a method includes requesting access to amedia drive located at a first station for loading a media cartridgetherein, wherein the media cartridge is physically located at a secondstation, and receiving a response indicating a multi-drop unidirectionaladdress specified in the response, wherein a shuttle car physicallymoves the media cartridge from the second station to the first station.

In another general embodiment, a computer program product for managingat least one logical library includes a computer readable storage mediumhaving computer readable program code embodied therewith, the computerreadable program code including computer readable program codeconfigured to request access to a media drive located at a first stationfor loading a media cartridge therein, wherein the media cartridge isphysically located at a second station, and computer readable programcode configured to receive a response indicating a multi-dropunidirectional address specified in the response, wherein a shuttle carphysically moves the media cartridge from the second station to thefirst station.

In another general embodiment, a system includes a plurality of logicallibraries, each logical library including at least one sequential accessmedia drive, at least one local station for sending and/or receivingshuttle cars to and/or from the plurality of logical libraries, andsequential access media for storing data therein. The system alsoincludes a library manager for communicating with the plurality oflogical libraries, wherein the library manager controls movementoperations of a plurality of shuttle cars along one or more shuttlepathways, wherein each of the shuttle cars are for transporting asequential access medium between any of the plurality of logicallibraries, wherein the one or more shuttle pathways connect the stationsin a multi-drop arrangement, wherein each destination station isrepresented by a unique export-only address, wherein all source stationsare represented by a common import-only address, and wherein an importelement address for a sequential access medium transferred from a firststation is different than an export element address for the sequentialaccess medium transferred to the first station.

According to one embodiment, a multi-drop physical connection thatallows the tape equivalent of “direct flights” between any pair oflibraries in the image is presented. This multi-drop physical connectionallows for faster transfers between libraries and also supports a muchhigher degree of parallelism in the system since intermediary librariesare not involved in some of the transfers and since multi-dropconnections scale much more cost-effectively than a point-to-pointsystem. This system, in one embodiment, can cost-effectively discoverand manage all of the possible logical connections with increasedparallelism in the system, than conventional, point-to-point systems.

The description herein is presented to enable any person skilled in theart to make and use the invention and is provided in the context ofparticular applications of the invention and their requirements. Variousmodifications to the disclosed embodiments will be readily apparent tothose skilled in the art and the general principles defined herein maybe applied to other embodiments and applications without departing fromthe spirit and scope of the present invention. Thus, the presentinvention is not intended to be limited to the embodiments shown, but isto be accorded the widest scope consistent with the principles andfeatures disclosed herein.

In particular, various embodiments of the invention discussed herein areimplemented using the Internet as a means of communicating among aplurality of computer systems. One skilled in the art will recognizethat the present invention is not limited to the use of the Internet asa communication medium and that alternative methods of the invention mayaccommodate the use of a private intranet, a Local Area Network (LAN), aWide Area Network (WAN) or other means of communication. In addition,various combinations of wired, wireless (e.g., radio frequency) andoptical communication links may be utilized.

The program environment in which one embodiment of the invention may beexecuted illustratively incorporates one or more general-purposecomputers or special-purpose devices such hand-held computers. Detailsof such devices (e.g., processor, memory, data storage, input and outputdevices) are well known and are omitted for the sake of clarity.

It should also be understood that the techniques of the presentinvention might be implemented using a variety of technologies. Forexample, the methods described herein may be implemented in softwarerunning on a computer system, or implemented in hardware utilizing oneor more processors and logic (hardware and/or software) for performingoperations of the method, application specific integrated circuits,programmable logic devices such as Field Programmable Gate Arrays(FPGAs), and/or various combinations thereof. In particular, methodsdescribed herein may be implemented by a series of computer-executableinstructions residing on a storage medium such as a physicalcomputer-readable medium. In addition, although specific embodiments ofthe invention may employ object-oriented software programming concepts,the invention is not so limited and is easily adapted to employ otherforms of directing the operation of a computer.

The invention can also be provided in the form of a computer programproduct comprising a physical computer readable medium having computercode thereon. A computer readable medium can include any physical mediumcapable of storing computer code thereon for use by a computer,including optical media such as read only and writeable CD and DVD,magnetic memory or medium (e.g., hard disk drive), semiconductor memory(e.g., FLASH memory and other portable memory cards, etc.), etc. Acomputer readable medium may also include a signal medium such as awire, network link, wireless link, etc. across which data and/orinstructions may be transmitted.

FIG. 1 illustrates a network architecture 100, in accordance with oneembodiment. In the context of the present network architecture 100, thenetworks 104, 106 may each take any form including, but not limited to aLAN, a WAN such as the Internet, WLAN, PSTN, internal telephone network,etc.

Further included is at least one data server 114 coupled to theproximate network 108, and which is accessible from the remote networks102 via the gateway 101. It should be noted that the data server(s) 114may include any type of computing device/groupware. Coupled to each dataserver 114 is a plurality of user devices 116. Such user devices 116 mayinclude a desktop computer, laptop computer, hand-held computer, printeror any other type of logic. It should be noted that a user device 1.1.1may also be directly coupled to any of the networks, in one embodiment.

A peripheral 120 or series of peripherals 120, e.g. facsimile machines,printers, networked storage units, etc., may be coupled to one or moreof the networks 104, 106, 108. It should be noted that databases,servers, and/or additional components may be utilized with, orintegrated into, any type of network element coupled to the networks104, 106, 108. In the context of the present description, a networkelement may refer to any component of a network.

FIG. 2 shows a representative hardware environment associated with auser device 116 and/or server 114 of FIG. 1, in accordance with oneembodiment. Such figure illustrates a typical hardware configuration ofa workstation having a central processing unit 210, such as amicroprocessor, and a number of other units interconnected via a systembus 212.

The workstation shown in FIG. 2 includes a Random Access Memory (RAM)214, Read Only Memory (ROM) 216, an I/O adapter 218 for connectingperipheral devices such as disk storage units 220 to the bus 212, a userinterface adapter 222 for connecting a keyboard 224, a mouse 226, aspeaker 228, a microphone 232, and/or other user interface devices suchas a touch screen and a digital camera (not shown) to the bus 212,communication adapter 234 for connecting the workstation to acommunication network 235 (e.g., a data processing network) and adisplay adapter 236 for connecting the bus 212 to a display device 238.

The workstation may have resident thereon an operating system such asthe Microsoft WINDOWS Operating System (OS), a MAC OS, a UNIX OS, etc.It will be appreciated that a preferred embodiment may also beimplemented on platforms and operating systems other than thosementioned. A preferred embodiment may be written using JAVA, XML, C,and/or C++ language, or other programming languages, along with anobject oriented programming methodology. Object oriented programming(OOP), which has become increasingly used to develop complexapplications, may be used. An interface 134 may also be provided forcommunication between the tape drive and a host (integral or external)to send and receive the data and for controlling the operation of thetape drive and communicating the status of the tape drive to the host,all as will be understood by those of skill in the art.

It will be clear that the various features of the foregoingmethodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will also be clear to one skilled in the art that the methodology ofthe present invention may suitably be embodied in a logic apparatuscomprising logic to perform various steps of the methodology presentedherein, and that such logic may comprise hardware components or firmwarecomponents.

It will be equally clear to one skilled in the art that the logicarrangement in various approaches may suitably be embodied in a logicapparatus comprising logic to perform various steps of the method, andthat such logic may comprise components such as logic gates in, forexample, a programmable logic array. Such a logic arrangement mayfurther be embodied in enabling means or components for temporarily orpermanently establishing logical structures in such an array using, forexample, a virtual hardware descriptor language, which may be storedusing fixed or transmittable carrier media.

It will be appreciated that the methodology described above may alsosuitably be carried out fully or partially in software running on one ormore processors (not shown), and that the software may be provided as acomputer program element carried on any suitable data carrier (also notshown) such as a magnetic or optical computer disc. The channels for thetransmission of data likewise may include storage media of alldescriptions as well as signal carrying media, such as wired or wirelesssignal media.

Embodiments of the present invention may suitably be embodied as acomputer program product for use with a computer system. Such animplementation may comprise a series of computer readable instructionseither fixed on a tangible medium, such as a computer readable medium,for example, diskette, CD-ROM, ROM, or hard disk, or transmittable to acomputer system, via a modem or other interface device, over either atangible medium, including but not limited to optical or analoguecommunications lines, or intangibly using wireless techniques, includingbut not limited to microwave, infrared or other transmission techniques.The series of computer readable instructions embodies all or part of thefunctionality previously described herein.

Those skilled in the art will appreciate that such computer readableinstructions can be written in a number of programming languages for usewith many computer architectures or operating systems. Further, suchinstructions may be stored using any memory technology, present orfuture, including but not limited to, semiconductor, magnetic, oroptical, or transmitted using any communications technology, present orfuture, including but not limited to optical, infrared, or microwave. Itis contemplated that such a computer program product may be distributedas a removable medium with accompanying printed or electronicdocumentation, for example, shrink-wrapped software, pre-loaded with acomputer system, for example, on a system ROM or fixed disk, ordistributed from a server or electronic bulletin board over a network,for example, the Internet or World Wide Web.

Communications components such as input/output or I/O devices (includingbut not limited to keyboards, displays, pointing devices, etc.) can becoupled to the system either directly or through intervening I/Ocontrollers.

Communications components such as buses, interfaces, network adapters,etc. may also be coupled to the system to enable the data processingsystem, e.g., host, to become coupled to other data processing systemsor remote printers or storage devices through intervening private orpublic networks. Moderns, cable modem and Ethernet cards are just a fewof the currently available types of network adapters.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer to offer service on demand.

Now referring to FIG. 3, a system 300 is shown according to oneembodiment. Note that some of the elements shown in FIG. 3 may beimplemented as hardware and/or software, according to variousembodiments. The system 300 includes a Library Manager (LM) 306 forcommunicating with a plurality of Logical Libraries 304 having dataorganized therein and stored on sequential access media 302 therein, andfor managing movement operations of a plurality of shuttle cars 314along one or more shuttle pathways 308. Each of the Logical Libraries304 may include at least one local station 320 for sending and/orreceiving shuttle cars 314 to and/or from the plurality of LogicalLibraries 304. Each of the shuttle cars 314 are for transporting asequential access medium 302 between any of the stations 320, and theshuttle pathways 308 connect the stations 320 in a multi-droparrangement.

A source station is one which is sending a sequential access medium to adestination station, according to one approach. For each local station320 in a Logical Library 304, each of the possible destination stationsare represented by a unique export-only address, and all possible sourcestations are represented by a common import-only address.

The Library Manager 306 may be implemented, for example, on a serverwith software and/or logic, integrated into a physical library, etc. Anillustrative Library Manager 306 that may be modified to include thefeatures and/or operations disclosed herein includes Automated CartridgeSystem Library Software (ACSLS) from Oracle Corporation, 500 OracleParkway, Redwood Shores, Calif. 94065. The Logical Libraries 304 in someapproaches may include a set of data organizations which may be physicalor logical.

In one embodiment, the system 300 may also include logic operable toinstruct one of the shuttle cars 314 to transfer a first sequentialaccess medium 302 from a first station (such as one located in LogicalLibrary LL1A) to a second station (such as one located in LogicalLibrary LL2A). Each of the Logical Libraries 304 may include at leastone sequential access media drive 322, and each station 320 may haveaccess to one or more sequential access media drives 322. The one ormore shuttle pathways 308 may also allow for direct transfers ofsequential access media 302 between any of the stations 320, in anotherapproach.

According to one embodiment, the first sequential access medium may betransferred when each of the at least one drive of the first LogicalLibrary is in use, and the system 300 may also include logic operable tocause the at least one drive of the second Logical Library to readand/or write from and/or to the first sequential access medium, e.g.,after the medium is received at a station of the second Logical Library.

In one embodiment, the sequential access media 302 may be magnetic tapemedia housed in magnetic tape cartridges.

In some embodiments, the system 300 may also include a first network,such as a Storage Area Network (SAN) 310 connecting the Library Manager306 to the plurality of Logical Libraries 304 and connecting the LibraryManager 306 to the shuttle pathways 308.

In more embodiments, the system 300 may include a second network, suchas a Local Area Network (LAN) 316 connecting the plurality of LogicalLibraries 304, and the Library Manager 306 to a system administrator 318for controlling operations thereof. The system administrator 318 may bea terminal, a computer system, a processor, etc., and may be controlledby an operator thereof for some or all commands.

The sequential access media drives 322 may be used to access data storedon a plurality of sequential access media 302 for storing data that isorganized into the Logical Libraries 304, in one approach.

Additionally, in some approaches, the multi-drop unidirectional addressmay be a unique unidirectional connected media changer (CMC)import/export element (IEE) address, as described previously. In someapproaches, each of the local stations may have the capability ofrepresenting 15 potential destinations, but of course, more or lessconnections may be possible, and each local station may not have themaximum number of connections. In more approaches, each of the pluralityof Logical Libraries 304 may have up to 16 local stations, but ofcourse, more or less local stations may be included for each LogicalLibrary 304.

According to another embodiment, the plurality of sequential accessmedia 302 may be magnetic tape, optical media, etc. Each sequentialaccess media 302 may be readable by a sequential access media drive 322,according to one approach, such as a tape drive, optical drive, etc.

In one approach, commands from the Library Manager 306 may betransmitted to the plurality of Logical Libraries 304 over at least onenetwork connection, and commands from the Library Manager 306 may betransmitted to the shuttle pathways 308 over the at least one networkconnection.

In another approach, the system 300 may include logic for creating amapping of multi-drop unidirectional addresses representing the stations320. The mapping may use unidirectional addressing to represent allpossible transfers of sequential access media 302 between the stations320.

According to another approach, command line instructions from a systemadministrator 318 to at least one of the Library Manager 306 and theplurality of Logical Libraries 304 may be executed by the at least oneof the Library Manager 306 and the plurality of Logical Libraries 304.This allows an operator, working from the system administrator 318, tocontrol operations of the system 300, either through the Library Manager306 or the plurality of Logical Libraries 304, in some approaches.

In yet another approach, an import element address for a sequentialaccess medium 302 transferred from a first station (such as a station inLogical Library LL1A) may be different than an export element addressfor the sequential access medium 302 transferred to the first station.

Each library string may support up to 16 local stations (1 per activeframe), according to one embodiment. Each local station may support upto 15 potential destinations (including a round-trip back to itself), inone approach. Each destination may be addressable as a CMC IEE addressof 2XZh where X represents the X-axis of the sending library string andZ represents the Z-axis for that specific connection, according to oneapproach. Thus a single connection may be reported as shown in Table 1,below, in one embodiment. In each Logical Library, however, the X valuemay be different, since it is unique to the sending (reporting) librarystring, in preferred embodiments.

TABLE 1 2X1h 2X2h 2X3h 2X4h ID = AAA ID = BBB ID = CCC ID = DDD 2X5h2X6h 2X7h 2X8h ID = EEE ID = FFF ID = GGG ID = HHH 2X9h 2XAh 2XBh 2XChID = JJJ ID = KKK ID = LLL ID = MMM 2XDh 2XEh 2XFh ID = NNN ID = OOO ID= PPP

To further elaborate, the SCSI standard allows import/export elementaddressing to be bidirectional (import and export via the same address)or unidirectional (import-only or export-only). The standard seems toassume (but does not require) that element addressing for connectedmedium changers is bidirectional since this is the typical mechanicalimplementation.

Virtualizing a single N-drop connection with bidirectional addressing,using conventional techniques, would require N*(N−1)/2 uniqueidentifiers (1+2+3 . . . +N). A connection to 15 shuttle stations(library strings) would require 105 unique identifiers. Furthermore,this requires that the transport of a cartridge include communicatingthe source station identity in order to properly report cartridgearrival at the bidirectional address uniquely tied to the sourcestation. This source station identity either must be stored in moreexpensive nonvolatile storage during transport or accommodations must bemade to handle the volatility of this information, e.g., a power lossduring transport of a cartridge.

Accordingly, for a first library at Z-axis position 3 on a multi-dropconnection, address 2X0 for the first library is an import-capableaddress that is used for detecting the arrival of a cartridge from anyother library, in one approach. However, address 2X3 reported by allother libraries on the same multi-drop connection is an export-onlyaddress representing the destination of the first library, in the sameapproach. With this approach, a unique identifier can be associated withthe destination (in this example, the first library) and only N uniqueidentifiers are required for a single N-drop connection.

In one embodiment, the mapping uses unidirectional addressing torepresent all possible transfers across the multi-drop implementation.Thus, the element address for the import of a cartridge from a firstlibrary is different from the element address for the export of acartridge to the first library. However, a single import address is usedper local station for the import of a cartridge from any potentialsource station (source-agnostic import addressing), in some approaches.With this approach, the import-only address need only have a uniqueidentifier that is associated with the local station, according to oneembodiment. Furthermore, the transport of a cartridge does not includecommunicating the source station identity, in some embodiments, whichreduces cost and/or complexity.

Now referring to FIG. 4, a method 400 is shown according to oneembodiment. The method 400 may be carried out in any desiredenvironment, including but not limited to, those shown in FIGS. 1-3,according to various embodiments. Of course, the method 400 may includemore or less operations than those described below, and shown in FIG. 4,as would be known to one of skill in the art.

In one preferred embodiment, the operations in FIG. 4, including anyoptional operations as one of skill in the art may choose to implement,may be carried out by a Library Manager, as described previously.

In operation 402, access is requested to a media drive located at afirst station for loading a media cartridge therein, with the mediacartridge being physically located at a second station.

Each of the stations may be located in one of a plurality of LogicalLibraries, with each Logical Library being represented by a dedicatedLibrary Manager, according to one embodiment. However, these dedicatedLibrary Managers may be rendered moot once an overall Library Manager isestablished, or they may continue to function partially or fully underthe control of the overall Library Manager.

In operation 404, a response is received indicating a multi-dropunidirectional address specified in the response. This response may besent by the Logical Library, a Library Manager associated with theLogical Library, or any other system, device, etc.

The multi-drop unidirectional address specified in the response may bebased on any factor, as would be known in the art, such as location,proximity to the first Logical Library, loading in the Logical Libraryhaving the available drive, etc.

In another embodiment, the method 400 may include checking for lockedshuttle cars that are not being used and causing any locked shuttle carsnot being used to become unlocked. This frees up shuttle cars for usewhen they are unnecessarily being locked, speeding up the process ofdata access in the system. In some further embodiments, the checking maybe performed in any number of ways as known in the art, such asperiodically (every so often, every 1/10 second, every second, every 10seconds, etc.), after each shuttle car call, after a predeterminednumber of shuttle car calls, etc.

According to one approach, the media drives may preferably be magnetictape drives and the media cartridges may preferably be magnetic tapecartridges. Of course, other types of media and media drives may also beused, as known to one of skill in the art.

In one approach, the method 400 may include optional operation 406,where a mapping is created of multi-drop unidirectional addressesrepresenting a plurality of stations, wherein the mapping usesunidirectional addressing to represent all possible transfers of mediacartridges between the plurality of stations.

In another approach, an import element address for the media cartridgetransferred from the second station may be different than an exportelement address for the media cartridge transferred to the secondstation.

In another embodiment, a computer program product for combiningcomponents of at least one Logical Library into a single image libraryis presented. The computer program product may be implemented in anyfashion as described in FIGS. 1-3, or as known in the art.

In one embodiment, the computer program product comprises a computerreadable storage medium having computer readable program code embodiedtherewith. The computer readable program code includes computer readableprogram code configured to request access to a media drive located at afirst station for loading a media cartridge therein, wherein the mediacartridge is physically located at a second station, and computerreadable program code configured to receive a response indicating amulti-drop unidirectional address specified in the response. Aspreviously described, a shuttle car physically moves the media cartridgefrom the second station to the first station.

In additional embodiments, the computer readable program code mayinclude computer readable program code configured to check for lockedshuttle cars that are not being used, and computer readable program codeconfigured to cause any locked shuttle cars not being used to becomeunlocked. The checking may be performed periodically, after each shuttlecar call, after a predetermined number of shuttle car calls, etc.

In another embodiment, the computer readable program code may includecomputer readable program code configured to create a mapping ofmulti-drop unidirectional addresses representing a plurality ofstations, wherein the mapping uses unidirectional addressing torepresent all possible transfers of media cartridges between theplurality of stations.

In another embodiment, the computer readable program code may includecomputer readable program code configured to support a floating homelogical library for each media cartridge that is moved between logicallibraries, as previously described.

According to another embodiment, an import element address for the mediacartridge transferred from the second station is different than anexport element address for the media cartridge transferred to the secondstation.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A system, comprising: a library manager forcommunicating with a plurality of logical libraries having dataorganized therein and stored on sequential access media therein, whereinthe library manager controls movement operations of a plurality ofshuttle cars along one or more shuttle pathways, wherein each of theshuttle cars are for transporting a sequential access medium between anyof the plurality of logical libraries, wherein each of the logicallibraries comprises at least one local station for sending and/orreceiving shuttle cars to and/or from the plurality of logicallibraries, wherein the one or more shuttle pathways connect the stationsin a multi-drop arrangement, wherein each destination station isrepresented by a unique export-only address, and wherein all sourcestations are represented by a common import-only address.
 2. The systemof claim 1, further comprising: the plurality of logical libraries: andlogic operable to instruct one of the shuttle cars to transfer a firstsequential access medium from a first logical library to a secondlogical library, wherein each of the logical libraries comprises atleast one sequential access media drive, wherein the one or more shuttlepathways allow for direct transfers of sequential access media betweenany of the plurality of logical libraries.
 3. The system of claim 2,wherein the first sequential access medium is transferred when each ofthe at least one drive of the first logical library is in use, andfurther comprising logic operable to cause the at least one drive of thesecond logical library to read and/or write from and/or to the firstsequential access medium.
 4. The system of claim 2, further comprisinglogic for creating a mapping of multi-drop unidirectional addressesrepresenting the stations, wherein the mapping uses unidirectionaladdressing to represent all possible transfers of sequential accessmedia between the stations.
 5. The system of claim 4, wherein an importelement address for a sequential access medium transferred from a firststation is different than an export element address for the sequentialaccess medium transferred to the first station.
 6. The system of claim1, wherein the multi-drop unidirectional address comprises a uniqueunidirectional connected media changer (CMC) import/export element (IEE)address.
 7. A method, comprising: requesting access to a media drivelocated at a first station for loading a media cartridge therein,wherein the media cartridge is physically located at a second station;and receiving a response indicating a multi-drop unidirectional addressspecified in the response, wherein one shuttle car of a plurality ofshuttle cars physically moves the media cartridge from the secondstation to the first station via one or more shuttle pathways thatconnect the stations in a multi-drop arrangement, wherein eachdestination station is represented by a unique export-only address, andwherein all source stations are represented by a common import-onlyaddress.
 8. The method of claim 7, further comprising creating a mappingof multi-drop unidirectional addresses representing a plurality ofstations, wherein the mapping uses unidirectional addressing torepresent all possible transfers of media cartridges between theplurality of stations.
 9. The method of claim 7, wherein an importelement address for the media cartridge transferred from the secondstation is different than an export element address for the mediacartridge transferred to the second station.
 10. The method of claim 7,wherein a first logical library comprises the first station and aplurality of drives configured to access media cartridges, wherein asecond logical library comprises the second station and a plurality ofdrives configured to access media cartridges, wherein the mediacartridge is transferred when all drives of the first logical libraryare in use, and further comprising: causing a drive of the secondlogical library to read and/or write from and/or to the media cartridge;and creating a mapping of multi-drop unidirectional addressesrepresenting the stations, wherein the mapping uses unidirectionaladdressing to represent all possible transfers of media cartridgesbetween the stations, and wherein the one or more shuttle pathways allowfor direct transfers of media cartridges between any of the logicallibraries.
 11. The method of claim 7, wherein an import element addressfor the media cartridge when transferred from the first station isdifferent than an export element address for the media cartridge whentransferred to the first station.
 12. The method of claim 7, wherein themulti-drop unidirectional address comprises a unique unidirectionalconnected media changer (CMC) import/export element (IEE) address.
 13. Acomputer program product for managing at least one logical library, thecomputer program product comprising: a non-transitory computer readablestorage medium having computer readable program code embodied therewith,the computer readable program code comprising: computer readable programcode configured to request access to a media drive located at a firststation of a first logical library for loading a media cartridgetherein, wherein the media cartridge is physically located at a secondstation of a second logical library; and computer readable program codeconfigured to receive a response indicating a multi-drop unidirectionaladdress specified in the response; and computer readable program codeconfigured to instruct one shuttle car of a plurality of shuttle cars tophysically move the media cartridge from the second station to the firststation via one or more shuttle pathways that connect the stations in amulti-drop arrangement that allows for direct transfers of mediacartridges between any of the logical libraries.
 14. The computerprogram product of claim 13, further comprising computer readableprogram code configured to create a mapping of multi-drop unidirectionaladdresses representing a plurality of stations, wherein the mapping usesunidirectional addressing to represent all possible transfers of mediacartridges between the plurality of stations.
 15. The computer programproduct of claim 13, wherein an import element address for the mediacartridge transferred from the second station is different than anexport element address for the media cartridge transferred to the secondstation.
 16. The computer program product of claim 13, wherein eachdestination station is represented by a unique export-only address, andwherein all source stations are represented by a common import-onlyaddress.
 17. A system, comprising: a plurality of logical libraries,each logical library comprising: at least one sequential access mediadrive; at least one local station for sending and/or receiving shuttlecars to and/or from the plurality of logical libraries; and sequentialaccess media for storing data therein; and a library manager forcommunicating with the plurality of logical libraries, wherein thelibrary manager controls movement operations of a plurality of shuttlecars along one or more shuttle pathways, wherein each of the shuttlecars are for transporting a sequential access medium between any of theplurality of logical libraries, wherein the one or more shuttle pathwaysconnect the stations in a multi-drop arrangement, wherein eachdestination station is represented by a unique export-only address,wherein all source stations are represented by a common import-onlyaddress, and wherein an import element address for a sequential accessmedium transferred from a first station is different than an exportelement address for the sequential access medium transferred to thefirst station.
 18. The system of claim 17, further comprising: logicoperable to instruct one of the shuttle cars to transfer a firstsequential access medium from a first logical library to a secondlogical library, the first sequential access medium being transferredwhen each of the at least one drive of the first logical library is inuse; logic operable to cause the at least one drive of the secondlogical library to read and/or write from and/or to the first sequentialaccess medium; and logic operable to create a mapping of multi-dropunidirectional addresses representing the stations, wherein the mappinguses unidirectional addressing to represent all possible transfers ofsequential access media between the stations, and wherein the one ormore shuttle pathways allow for direct transfers of sequential accessmedia between any of the plurality of logical libraries.
 19. The systemof claim 18, wherein an import element address for a sequential accessmedium transferred from a first station is different than an exportelement address for the sequential access medium transferred to thefirst station.
 20. The system of claim 18, wherein the multi-dropunidirectional address comprises a unique unidirectional connected mediachanger (CMC) import/export element (IEE) address.